Engine Stumbles at High Speed at full throttle!!

[dquiroga07]

hey guys

im having this issue that came up recently. My MS6 stumbles when im at full throttle and at high speed like at 100 or more, other than that the car runs perfect. has anyone else experienced the same issue. and if so what did you do to correct. and if any one has a solution i would more than appreciate it.

[m4tic]

did you replace your fuel pump internals?
DI fuel pressure could be crapping out...

i just put my stock parts in because of this issue

[dquiroga07]

no i didnt replace any fuel pump internals all stock. but the issue is very weird. if i go just beyond full throttle the issue does not show up at that high speed. I wanna say it could be the clutch that has the issue, because it only happens when going full power. driving around town the engine does not stumble at all or while going full throttle thru 1st and 3rd. ill record a video of what is happening and post it.

[KTsuchiya]

Some Issues to check:

1. Must use 93 Octane
2. Check engine oil levels, did u upgrade to 5w-40??

[dquiroga07]

Oil Levels are good and still using factory spec full synthetic 5w-30, and always used 93 octane. i think its a different issue. havent had time to make a video but will this weekend

[KTsuchiya]

Oil Levels are good and still using factory spec full synthetic 5w-30, and always used 93 octane. i think its a different issue. haven't had time to make a video but will this weekend

That's good. Yeah, I think a video will definitely help out. I know sometimes that my engine hesitates when I'm on the highway as well going 70+. When I step on the throttle and off and then again to go over 70, it hesitates. This issue has been discussed on this forum already and seems to be related to a turbo sealing issue.

[Evolved]

How old are the spark plugs? My car did that when I first got it and I put in a set of Denso ITV22's and the problem went away.

[Blendercloud]

How old are the spark plugs? My car did that when I first got it and I put in a set of Denso ITV22's and the problem went away.

This would be my suggestion. It sounds like you've got at least one fouled plug. Also, do you have a DashHawk to datalog knock and fuel pressure with?

[dquiroga07]

My sparkplugs are the original ones when i bought the car in 07, and i dont have a dashhawk i might have to invest in one. and ill get some plugs and hope the problem goes away. and engine does not hesitate, it feels like when you shift really hard into gear. i gotta get the vid for you guys, but gotta do it at night on the highway (less traffic and no cops!!!)

[dquiroga07]

i finally have a video of the issue

http://www.youtube.com/watch?v=ATA4gN907Fk

listen carefully and let me know what you guys think??

[neoshade]

There are other threads on this issue. I'll post a link if I find them. But y'know - Search first, ask questions later.

Spark Plug Info & Discussion.
http://www.mazdas247.com/forum/showthread.php?t=123749775&referrerid=70087

Delay in Power under Wide Open Throttle
http://www.mazdas247.com/forum/showthread.php?t=123758924

[neoshade]

This may be one of two things:

1: Plugs

Spark plug recommended temp is relative to *Speed*
That is to say it's a product of throttle, force & time.
So, you should have this same problem if you warm up the engine with a bit of driving, and then accelerate heavily for a sustained period.

You may need a colder plug.
Recommended spark plug temp is based on avoiding ping/knock at the high end (and fouling at the low end)

Conclusion 1: your engine is being throttled back by the ECU when it records a ping or knock. Replace your plugs. Check forums to make sure you get the right ones.

2: Fuel Pump / Filter

Fuel consumption is, of course, also relative to speed.
This was mentioned above, but if your pumps (yes, you have TWO fuel pumps in an MS6) are in need of repair, or the fuel filter needs replacement, this may happen.

Conclusion 2: Possibly a direct fuel issue, but likely an automatic down-throttle by the ECU (computer) due to engine readings going out of spec. Call dealership or keep forum searching!

Hope this helps.

[Speedkid]

My car has a misfire could that be spark plugs?

[Nigelo]

I've got a very similar set of symptoms from my MS3. Only occured after my remap though, and at 2250rpm in 5th/6th going slowly onto a WOT.
I'm pretty much convinced it's the A/F mix going lean - at low rpm the cam lobe isnt rotating fast enough to power the HPF pump into providing enough fuel. The remap has brought the situation as more fuel is being asked for by the ecu earlier to provide the higher bhp/torque.

My solution - Im buying upgraded pump internals! I'll let you know how I get on... could be a few months though, to save up the cash (Christmas is expensive :) )